Should I uninstall CS5.5?

I have both installed right now and what seems to happen is that the first time you try to open a project from 5.5, it actually creates a new project (without changing the original) and you can place that in a separate cs6 folder. So it seems like each version actually creates their own specific projects. Don't know if you can open a CS6 project in 5.5 (don't know why you'd want to though).

Good point, I can't tell you how many times I needed someone to open a final cut project (I was always on the newest version) on their machine and they would have to upgrade before they could work with me.